A ligament is a piece of fibrous tissue which connects one bone to another.
Ligaments are frequently damaged (e.g., detached or torn or ruptured, etc.) as the result of injury and/or accident. A damaged ligament can impede proper motion of a joint and cause significant pain.
Various procedures have been developed to repair or replace a damaged ligament. The specific procedures used depend on the particular ligament which is to be restored and on the extent of the damage.
One ligament which is frequently damaged as the result of injury and/or accident is the anterior cruciate ligament (ACL). Looking now at FIG. 1, the ACL 5 extends between the top of the tibia 10 and the bottom of the femur 15. A damaged ACL can cause instability of the knee joint and cause substantial pain and arthritis.
Numerous procedures have been developed to restore the ACL through a graft ligament replacement. In general, and looking now at FIG. 2, these ACL replacement procedures involve drilling a bone tunnel 20 through tibia 10 and up into femur 15. Then a graft ligament 25, consisting of a harvested or artificial ligament or tendon(s), is passed through the tibial portion 30 of tunnel 20 (sometimes referred to as “the tibial tunnel”), across the interior of the joint, and up into the femoral portion 35 of tunnel 20 (sometimes referred to as “the femoral tunnel”). Then a distal portion of graft ligament 25 is secured in femoral tunnel 35, and a proximal portion of graft ligament 25 is secured in tibial tunnel 30.
There are numerous ways in which graft ligament 25 may be positioned in tunnel 20 and secured in position.
One such way is disclosed in U.S. Pat. No. 5,918,604, issued Jul. 6, 1999 to Whelan for METHOD OF LOADING TENDONS INTO THE KNEE. According to this patent, the ligament may be towed up tibial tunnel 30 and femoral tunnel 35 and then secured in femoral tunnel 35 with a crosspin.
More particularly, and looking now at FIG. 3, the bone tunnel 20 is formed by drilling through tibia 10 and up into femur 15, whereby to form tibial tunnel 30 and femoral tunnel 35. Then a transverse bone tunnel 40 is formed in femur 15 so that transverse bone tunnel 40 intersects femoral tunnel 35. Bone tunnel 20 bifurcates transverse bone tunnel 40 into two tunnel portions, a first transverse bone tunnel portion 45 and a second transverse bone tunnel portion 50.
After transverse bone tunnel 40 has been formed, a flexible member 55 is used to draw graft ligament 25 up into place.
More particularly, according to the aforementioned U.S. Pat. No. 5,918,604, this is done by threading flexible member 55 through transverse bone tunnel 40. Then a crochet-hook device (not shown in FIG. 3) is passed up tibial tunnel 30, across the interior of the knee joint, and up femoral tunnel 35. The crochet-hook device is used to hook flexible member 55 at the intersection of bone tunnel 20 and transverse bone tunnel 40. Then the crochet-hook device is used to pull flexible member 55 down femoral tunnel 35, across the interior of the knee joint, down tibial tunnel 30, and out the front side of tibia 10. Next, graft ligament 25 is looped over flexible member 55 (FIG. 3). One or both free ends of flexible member 55 is/are then pulled away from femur 15, whereby to pull flexible member 55, and hence the looped graft ligament 25, up tibial tunnel 30, across the interior of the knee joint, and then up into femoral tunnel 35 (FIG. 4).
Once flexible member 55 and graft ligament 25 have assumed the position shown in FIG. 4, the graft ligament may be retained in that position by passing a cannulated crosspin 60 over flexible member 55 into transverse bone tunnel 40 so that the crosspin extends under graft ligament 25 and supports the looped graft ligament within femoral tunnel 35. Then flexible member 55 is withdrawn from the surgical site.
Unfortunately, the method taught in U.S. Pat. No. 5,918,604 suffers from a number of drawbacks.
For one thing, use of this method can result in erosion of the patient's bone. More particularly, and looking now at FIG. 5, flexible member 55 must first be drawn down femoral tunnel 35, across the interior of the knee joint, and then down tibial tunnel 30 in order to pick up graft ligament 25; and then later, flexible member 55 must be drawn back up tibial tunnel 30, across the interior of the knee joint, and then back up femoral tunnel 35 in order to carry graft ligament 25 into position. These actions cause flexible member 55 to engage the bone which is located at the intersection of femoral tunnel 35 and transverse bone tunnel 40, i.e., to engage the bone edges 65 (FIG. 5). This engagement between flexible member 55 and bone edges 65 can cause bone edges 65 to be eroded. This erosion can be particularly significant where substantial forces are required to draw flexible member 55 out of bone tunnel 20 (e.g., where a metallic flexible member 55 is used); or when substantial forces are required to draw flexible member 55 and graft ligament 25 up bone tunnel 20 (e.g., where graft ligament 25 makes a tight engagement with the walls of bone tunnel 20).
For another thing, the method taught in U.S. Pat. No. 5,918,604 can be tedious to practice. More particularly, when flexible member 55 and ligament graft 25 are in the position shown in FIG. 5, flexible member 55 will form the angle θ; however, when flexible member 55 and ligament graft 25 are in the position shown in FIG. 6, flexible member 55 will form a different angle θ. In this respect it will be appreciated that it will be considerably more difficult to pull graft ligament 25 upwards as the angle θ increases from the position shown in FIG. 5 to the position shown in FIG. 6.